The present invention relates to a method and a corresponding system for converting a digital signal to an analog signal.
Digital to analog conversion is widely applied in electronic signal processing. Known conversion techniques use so-called current steering Nyquist digital to analog converters (DAC) summing binary weighted current sources to form the analog signal. Such Nyquist DACs offer high-speed conversion with relatively few current sources. The output analog signal shows inaccuracy due to mismatch of the weighted current sources, in particular with large current range. Furthermore a hardware filter is necessary, e.g. a low pass filter, for filtering the output signal to suppress harmonic content in the output signal.
Another known conversion technique uses a so-called multi-bit Delta-Sigma converter summing only equal current sources and thus offering high accuracy at reduced conversion speed. A subset of n out of in total N current sources can be selected using a dynamic element matching (DEM) unit to further improve accuracy by averaging out mismatch errors of the individual equal current sources. A hardware filter is still necessary for filtering the output signal.